1. Field of the Invention
The invention generally relates to an apparatus and method for testing the performance of a laser system and, in particular, the invention relates to a performance tester apparatus for a surgical laser system and method therefor which is provided with a target that permits checking the forms and accuracy of both a visible laser aiming beam and an invisible laser cutting beam to insure that the axis of the laser cutting beam is accurate and in coincidence with the axis of the laser aiming beam and to further check the size and mode of the laser cutting beam.
2. Description of the Prior Art
Generally, a surgical laser system utilizes a pair of laser beam (i.e. a visible laser aiming beam which is a relatively low energy laser beam provided by a Helium-Neon (HeNe) gas laser and an invisible laser cutting beam which is a relatively high energy laser beam provided by a Carbon Dioxide (CO.sub.2) gas laser which in operation are narrowly confined within an articulated arm assembly. A handpiece attached to the end of the arm assembly is manipulated by the surgeon usually at the beginning of a laser type surgical operation to achieve a very accurate or precise focus or to aim the laser cutting beam and thereby point or focus the cutting beam at the proper location within the field of the surgical operation.
Since the laser cutting beam is normally invisible to the human eye, a second laser beam, that is usually called a laser aiming beam, which can be seen because it used a laser light beam that is within the visible spectrum, is used to indicate the exact position of the laser aiming beam by means of a visible dot on the tissue of the surgical patient. When the surgeon has positioned the visible laser aiming beam to be at the desired focus or location, the surgeon then depresses a foot switch associated with the laser surgical system to effectively remove the visible laser aiming beam and activate the laser cutting beam and thereby make incisions for the laser surgical operation.
From this description, it is obvious that the alignment between the laser aiming beam and the laser cutting beam is very critical to the entire laser surgical procedure. The surgeon controlling the laser surgical operation must rely on the fact that the two beams are precisely aligned when an incision is made by the laser cutting beam. Obviously, if the optical systems that are associated with either or both the laser aiming beam or the laser cutting beam are out of alignment with respect to each other, then the focus or location of each of these two laser beams will not be coincident with the focus or location of the other of the two laser beams. Further, the size and mode (shape) of the laser cutting beam is also critical to the incision being made by the surgeon.
In practice, the surgeon previously utilized a combustible material such as a wooden tongue depressor as a target to test the operation and focus of the surgical laser system. The laser aiming beam was directed at the wooden tongue depressor and then the laser cutting beam was activated to determine how accurately the spot burned on the target wooden tongue depressor by the invisible laser cutting beam matches the visible location on the wooden tongue depressor of the visible laser aiming beam. The shape and uniformity of the burned area on the wooden tongue depressor was used to try to indicate whether or not the surgical laser system was functioning properly. However, a burnt area on a wooden target is not always a true indication of the proper or precise focus or size or mode of the laser cutting beam because of the lack of control over how much of the wood is burned or charred by the laser cutting beam or the energy or heat associated therewith.
The problems associated with the above described method previously utilized to try to check for proper orientation and operation of the surgical laser system was that it was very inexact and unreliable and no proper record of the test results was subsequently available to document proper operation of the laser surgical system. The present invention utilizes a more accurate performance tester apparatus for a surgical laser system which includes the use of a removable target located within the test fixture portion of the performance tester apparatus which replaces the handpiece of the laser surgical system to provide a permanent, accurate, and precise record of the proper operation and focus of the laser surgical system. Thus, the precise focus and location of the laser cutting beam with respect to the laser aiming beam can now be permanently recorded thereby insuring the reliability of the laser surgical system as well as a technique to protect the patent, the laser doctor, the surgical center, and the manufacturers of surgical laser systems from accidents due to an improperly aligned surgical laser system.